We can classify components of food on the basis of their function:
(A) Nutrients which give energy and promote growth and development of body:
(i) Carbohydrates
(ii) Fats
(iii) Protein
(B) Nutrients which help in formation of body,
(i) Protein
(ii) Mineral salts
(iii) water
(C) Nutrients which provide protection
(i) Vitamin
(ii) Mineral salts
(iii) Protein, water.